Apparatus particularly applicable to measurements of the calorific value of combustible fluids



i k Ilrl ITII MWGIEWEWMII|I I March 13, 1928.

H. N. PACKARD APPARATUS PARTICULARLY APPLICABLE TO MEASUREMENTS OF THE CALORIFIC VALUE OF COMBUSTIBLE FLUIDS Filed Jan. 28, 1921 A UNITED. STATES Patented Mar. 13, 1928.

PATENT (OFFICE.

HORACE N. PACKARD, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO THE CUTLER-HAM- MEIR MFG. (30., OF IIlIILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

APPARATUS PARTICULARLY APPLICABLE TO MEASURENIENTS OF THE CALORIFIC VALUE OF COMBUSTIBLE FLUIDS.

Application filed January 28,1921. Serial No. 0,61%.

This invention relates to apparatus particularly applicable to measurements of the calorific value of combustible fluids, together with certain novel methods which are subsidiary to certain known methods of effectng the foregoing result. The invention 1 also contemplates certain features having other advantageous applications.

In my prior Patent No.. 1,625,277, dated April 19, 1927, are disclosed a method and apparatus wherein constant volumetric proportions pftest gas, combustion air and cooling air are delivered, under like conditions of temperature, pressure and saturation, to

' a devicefor effecting combustion of the gas and transfer of the heat so liberated to the cooling air, theconsequent temperature rise of the latter being indicated whereby any variation in heating value'of the testgas,

causes a correspondingproportional change in the indicated temperature rise of the cooling fluid and the latter comprises a measure of the former.

Also in my prior pending application, Serial No. 438,954, filed January 21, 1921, are disclosed .a method and apparatus analogous to the foregoing but differing therefrom in that in such latter case the volumetric proportioning of the test gas and air is varied to maintaimsubstantially a con stant temperature rise of the cooling fluid, the degree and character of such regulation or proportion variation being utilized as a measure of the heating value of the test gas and being indicated as such.

The present application is in the nature of a continuation-or extension of both of said prior applications since the same covers features which are disclosed in said prior appli-,

cations but 'not specifically claimed therein. Moreover, most features of the present application are equally applicable to the teach ingsof either of said earlier applications.

The present invention has among its objects that of providing certain improvements in the aforementioned methods and apparatus tending towards greater accuracy and refinement of the resultsattained thereby.

Another object is that of providing an improved method of and apparatus for effecting combustion of the test gas.

Another object is that of providing im Another object is that of providing an improved method and apparatus to com ensate for heat losses incident to the eat exchange.

Another object is that of minimizing the amount of care and attention required for proper functioning of the apparatus. i

Another object is that of facilitating test of the apparatus employed to ascertain from time to time whether the same adheres to a given standard of operation and if no to also ascertain the degree of variation fforn such standard.

Another object is that of providing for ready and accurate adjustment to compensate for possible errors disclosed by the foregoing tests.

Another object is that of providing for compensation for possible errors due to temperature variations tending to influence the accuracy of the results obtained.

Other objects and advantages will hereinafter appear.

The accompanying drawing illustrates schematically anddiagrammatically a proposed form of the aforementioned apparatus and the same will now be described, it being understood that such apparatus may be modified in numerous ways within the scope of the appended claims.

Following herein the disclosure of the aforementioned prior applications, test gas, combustion air and cooling air are supplied under like conditions of pressure, temperature and saturation, and in regulated proportions by volume, to a burner for combustion of 2 the gas and combustion air and absorption by the cooling air of the heat so liberated. Resistance thermometers, or the like, are arranged in the stream of cooling air to be subiected 'respectivelyto the temperature of tie latter before and after the heat exchange, said resistance thermometers being connected in a Wheatstone bridge having associated devices arranged to be influenced thereby for o crating a suitable the test gas.

metric proportioning of the test gas and cooling air is maintained, the combustion air being also constantly proportioned to effect complete combustion of the gas." Any variation in heating value of the test gas thus tends to cause variation in the temperature difference of the resistance thermometers and such variation is utilized to actuate a rheostat in a manner to restore the balance of the Wheatstone bridge, the degree and character i of the rheostat regulation thus effected being indicated by the recorder.

Referring to the drawing the same illustrates an associated gas burner and heat exchange device indicated generally at 1,

both of said elements being of special construction. The three fluids aforementioned are supplied through suitable conduits to said device by means of pumps including a gas pump 2, a combustion air pump 3 and a cooling air pump 4, and preferably comprising separate wet displacement meter structures having a common liquid seal comprising water or other fluid contained within a tank 5. Said pumps-are further adapted to be power driven at speeds bearing a constant ratio to one another by means of a suitable motor 6 acting through power connections to be hereinafter described.

Resistance thermometers 7 and 8 are so associated with the device 1 as to be subjected respectively to the-temperature of the cooling fluid before and after the heat exchange. Said resistance thermometers are utilized in a W'lieatst'one bridge to control a galvanometer 9, having associated with its needle 10, a switch 11 having operated solenoid 12 which serves in conjunction wlth acontact drum 13, to be driven'by the motoi 6, to control the operating electro-1nagnets 14 and 15 of a ratcheting mechanism 16. Said ratcheting mechanism in turn is uti lized for varying the resistance of an adjustihg rheostat 17 connected with the \Vheatstone bridge; tively connected with the driven member of said rheostat whereby the former serves to indicate and record the degree and character of the rheostat adjustments required to maintain or restore the balance of the VVheatstone bridge upon variation in heating value of the test gas, the indications of the recorder thus constituting an accurate measure of such value of the gas.

through the tube 21.

Also a recorder 18 is opera-' motor as illustrated. The aforedescribed instrumentalities are adapted to function in general precisely as in said earlier copending application and since no broad novelty of such method or apparatus is claimed herein no further description of such instrumentalities is deemed necessary.

7 Referring more specifically" to the structure of the device 1', the same comprises a pair of concentrically"arranged and openended tubes 20 and 21 "which constitute the burner proper, said tubes being respectively provided with lateral inlet passages 22 and 23 connecting the interiors thereof respectively with a pair of chambers 24: and25. Each of said chambers is in turn adapted to communicate with an" associated common chamber 26 the latter being connected by a tube 27 with the discharge side of the combustion air pump 3. Similarly the chamber 24: is connected by conduit 28 with the discharge side of the gas pump 2. A pair of valves 29 and 30 serve respectively to control communication between the individual chambers 24 and 25 and their common communicating chamber 26. From. the foregoing arrangement it results that in the operation of the device the chamber 24: is filled with a mixture ofgas and combustion air, such mixture being conducted to the interior of the burner tube 20 by communicating passage 22. The chamber 25 on the other hand is adapted to contain only combustion air which is led through the conduit 23 Within the outer tube 21 of the burner. The valves 29 and 30 are preferably so adjusted that the mixture of gas and air within the chamber 24 is non-combustible, that is to say the proportion of air is preferably insuiiicient to support combustion of the gas,

whereby it results that the mixture arriving at the upper end of the tube 20 is incapable of combustion except by virtue of the additional supply of combustion air furnished The upper end of said tube 2.1 is preferably projected a material distance above the adjacent portion of the inner tube 20 for promoting an intimate mixture of such additional'supply of'combustion air with the aforedescribed non-combustible mixture of gas and air substantially at the point of combustion.

The foregoing construction and arrangemerit thus provide for supplying, to the burner, test gas'and air in quantities constantly proportionedto effect complete combustion, while separating or dividing the air so supplied .into primary and secondary streams, intermingling the former. stream with the supplied gas to effect preferably. a non-combustible mixture and supplying the latter stream to the burner to support and assist-in combustion of such mixture. Such expedient serves to promote reliability and steadiness of the combustion and to prevent tioned are preferably openand arranged to project below the level of the sealing liquid in the tank 5, thus permitting ready egress of any condensed vapor or other impurity which might tend to choke or clogthe burner while also maintaining a seal to prevent en trance of unmeasured atmospheric air or other extraneous substance.

A cap 31 having axially extended side walls is arranged aboveand about the upper end of the burner aforedescribed for causing the products of the aforedescribed combustion to flow downwardly in heat exchanging relationto a flow of cooling fluid and also to the flow of combustion gases prior to burning of the latter. The length of such return path of said combustion products as determined by the axial length of said cap is that such combustion products, prior to escape thereof, are cooled to substantially t e same temperature as that of the entering combustion gases and cooling" fluid. The foregoing arrangement serves to eliminate possible heat losses involving the'latent heat of vaporization of the water of combustion or of other combustion product which is adapted to undergo a similar change in its condition within the range of the temperatures involved. j

A tubular jacket 32 is arranged to surround the cap v31 aforedescribed, being adapted at its lower end to make a hermetically tight joint with the exterior of said cap. Said jacket preferably extends a material distance above saidcap, the upper end of the former being preferably open and un-- obstructed. A conduit 33 serves .to con nect the interior of said jacket with the discharge end of the cooling air pump 4.

An exterior cap 34 is arranged above and about the aforedescribed open end of the jacket 32, said cap being open at its lower end and providing a downward or return flow passage for the cooling air asthe same escapes from said jacket.

In practice such open lower end of the cap 34 is arranged at about the same elevation asthe upper end of the inner tube 20 of the burner, whereby the cooling airprior to escape thereof is constrained to flow about and in heat exchanging relation with the upward flowing column of such air within the jacket 32 to or even below the point of combustion.

The cooling air, after acting upon the re- 'sistance thermometer 8, is still at, 'approxn mately. the highest temperature attained during the heat exchange, and hence the aforedescribed reflexed flow of such are about the jacket 32 serves to minimize loss of heat of the heated cooling air within said jacket by convection or radiation to the atmosphere. i the length of of cooling air, ance thermometer 8, may be preheated to a degree sufficient to exactly compensate for any otherwise uncorrected heat losses inciexchange. For such pursuch reflexed flow, the stream dent to the heat pose the effective axial length of the cap 34; maybe made adjustable. The foregoing arrangement of the burner and heat vexchange device further provides for opposedflows of the fluids which are in heat exchanging relation to one another, whereby efficiency of the exchange is promoted.

The resistance'tliermometer 7 is preferably located as illustrated within the lower portion of the jacket 32 at a point sufficiently removed from the point of combustion to render the temperature of said thermometer determinable solely by the temperature of the entering cooling air and independent of the combustion. The, resistance thermom eter 8 on the other hand is located within the upper portion of the jacket 32 and preferably directly above the inner cap 31 whereby said thermometer is subjected to the temperature of the cooling fluid immediately following completion of the main heat exchange.

In the operation of the fluid pumps aforedescribed it is apparent that the three gases handled thereby are subjected to like'intimate contact with the sealing liquid whereby all of said gases are adapted to assume the temperature of said liquid and moreover to become saturated therewith at such common temperature. Further the interior of the tank 5 is preferably in open communication with atmosphere through the open top of said tank whereby both air pumps are adapted to draw directly from atmosphere and consequently the pressure of fluid entering said pumps is atmospheric pressure;

The test gas is admitted to the pump 2 through an intake conduit 35, a pressure regulating deviceindicated generally at 36 being provided for insuring that the pressureof the gas at the intake side of said gas pump shall be; similarly maintained at atmospheric pressure.

Said pressure regulating device preferably comprises a barrier 37 located within the conduit 35 and provided with a materially reduced opening 38 and an open ended branch pipe 39 connecting said conduit on the pump side of said barrier directly with the atmosphere. In operation the barrier serves to restrict the flow of gas therebeyond to a value which is able to escape through the pipe 39 without raising the A pressure upon-the pump side of said barrier above atmospheric pressure, whereas the outward flow of gas through said pipe 39 effectively before acting upon the resist- Also by suitably determining prevents induction of air into the pump. The gas so issuing from the pipe 39 is ordinarily ignited and burned to avoid pollution of the surrounding air. Such continuous eiilux of gas in appreciable quantities from said tube further serves to insure that the testgas drawn into the pump constitutes a true sample of the main supply undergoing test.

Thus provision is made for supplying test gas, combustion air and cooling air to the device 1 under like conditions of temperature, pressure and saturation and in constant volumetric proportions to one another, such proportioning moreover being un aliected by variation in speed of the motor 6.

However, it is to be observed that the aforedescribed constant volumetric proportioning of the several fluids will be maintained only if the relative capacities of the individual pumps continue unchanged,

' whereas owing to corrosion of the material of any of thepumps or to deposits of tar or other gas constituent within the gas pump such relative capacities of the pumps tend to vary from time to time to an extent which might if uncorrected. tend to introduce serious error into the indication or recording of the device.

For this reason the means to be now described are provided for checking the rela-' tive capacities of the gas and cooling air pumps, these being the two for which constant relative capacities are particularjy important, the two air pumps, moreover, being subjected to substantially similar conditions and therefore having less tendency to vary with reference to one another. It is, however, to be understood that similar means may, if desired, be provided for checking the relative capacities of the air pumps.

In practice the cooling air pump is ordi narily of considerably larger capacity than that of the gas pump and is driven at a materially higher speed than the latter, owing to the relatively large volume of air required to absorb the heat of combustion of the gas without an inconveniently large rise 'intemperature of such cooling fluid, whereas in the present device the speed ratio of said pumps is maintained constant during normal operation. However, for the purpose last described, a change speed transmission device is provided whereby the relativespeed of the two pumps may be so far changed as to render the volumetric rates of delivery of said pumps presumptively equal. fiuid'connections of the respective pumps are also commutated to cause both pumps to act upon the same body of fluid, preferabl air, and suitable indicating means are emp oyed for ascertaining the relative rates of action of said pumps, whereby it the speed ratio be maintained constantzthe relation of such rates of action upon the same body of fluid constitutes a measure of the relative capacity of the pumps.

In practice the illustrated system of slid- "delivery side of the cooling air pump may .be likewise connected ltll the interior of the gasometer. Under these conditions upon operation of the pumps the cooling air pump serves to force air into the gasometer while the gas pump serves simultaneously to exha ust air therefrom.- Thus any variation in relative rates of delivery of the two pumps will result in a change of volume of fluid within the gasometer bell with a consequent vertical movement of'the latter, the degree of such movement being indicated upon the illustrated scale. Said scale is prefer bly divided to indicate, percents of error in the indication of the complete device, whereby in testing or comparing similar complete devices whose indications difier to a known degree, the portion of such difference, that is to say, the error of one device assuming "the other as a standard, which is due to the foregoing cause is at'once ascertainable.

In practice it is preferable to continue the aforementioned test sufiiciently to efi'ect one or more exact revolutions of the cooling air pump thereby eliminating possible error due to unequal capacities of different portions of the pump. The corresponding relatively large number of revolutions of the gas pump ordinaril serves to obviate similar errors due to li e condition of said latter pump.

Since as aforestated, the gas pump is the i one having the greater tendency to change its internal capacity during service, the means now'to be described are provided for adjusting said pump to correct for variations in its capacity as disclosed by the foregoing test, it being of course understood that The the othen pumps may be provided with similar adjusting means if desired. 'In practice such means may advantageously comprise a plurality of adjusting screws 45 which provide for raising or lowering the gas pump bodily within the tank whereby a greater or lesser portion of its internal volume is brought above the level of the sealing liquid, and the desired pumping capacity regulation is effected. 1

Also the foregoingparts are preferably so pediting the aforedescribed adjustment.

In the operation of the complete device, it

A is desirable that the level of the sealing liquid be maintained substantially constant with reference to the height relation of the several pumps thereto since any material variation in such relation tends to impair the'accuracy of the results indicated. Also it is of importance to provide for draining the various fluid conduits of sealing liquid or other substances which may be condensed from or*otherwise deposited by such fluids between the individual pumps and the device -1.

To such end an auxiliary reservoir is provided Within the main liquid tank and adapted to contain aseparate reserve Supply of sealing liquid.

In practice the aforedescribed pumps are preferably mounted upon a common support 47 located within the tank and provided with.

an internal chamber 48 to contain such reserve fluid, the. level of fluid within such chamber being maintained somewhat below,

that of the tank. An overflow pipe 49 serves to connect the interior of said tank with the interior of said chamber and also to determine the height of liquidwithin the former.

Said support is further provided with a tubular port-ion 50 extending upwardly above the level of liquid in the tank and serving to connect the chamber 48 with the atmosextension 50 at any time,

or the like being preferably provided for inphere. A chain and'bucket 51, or other preferred type of pump is arranged preferably within the extension 50 and adapted to be driven by the motor 6 for conveying continuously from the chamber 48 to the tank a quantity of fluid somewhat in, excess of that which is lost from the tank due to evaporation and other causes. The excess'of liquid so supplied to the tank is adapted to flow back into thechamber by means of the weir 49. Also the several fluid conduits are provided with self draining tubes 52, 53, 54 and 55 extending within the chamber 48 and terminating below the surface of the liquid therein for sealing thereof. Liquid may be introduced. into the chamber. 48 through the a gauge glass-'56 dicating the height of liquid therein. 'No

definite height of liquid within the chamber need be maintained, provided the quantity suflicient to provide for contlnuous operation ofthe l pump 51 and also provided the level of liquid within the aforedescribed drain pipes be maintained well below the seals of the gaseous fluid pumps.

The resistance thermometers 7 and 8v may be constructed of any suitable material, such as nickel wire, which is adapted to change its resistance in accordance with temperature variations. Also it is desirable to construct throughout the Working range.- On the other hand the temperature resistance curve of nickel and of a number. of other suitable materials is substantially in the form of an arc of relatively large radius. Hence assuming the aforementioned similarity of said resistance thermometers, the same, owing to differences in the temperatures to which they are individually subjected, are not adapted, in the absence their respective ohmic values equally upon similar variation ofthe temperature of each,

of special provisions, to vary 4) such as would occur for example should the 1 temperature of .the cooling fluid, as determined by the temperature of the sealing liquid, be increased or decreased. Thus should the temperature of the sealin fluid be increased even a few degrees above its temperature at the time when the apparatus was adjusted the resistance thermometer 8 being subjected to the higher temperature will increase its resistance more than the resistance 7 whereby the indications of the device will tend to be in error to a proportional degree. In the case assumed the recorder would tend to indicate too high a heating value of the test gas. I

On the other hand the specific heat of the cooling fluid,'if air, rises upon increase of its content .of vapor of the sealing liquid, which content in turn likewise increases with a rise' in temperature of said sealing liquid. Thus for a higher tank temperature the cooling fluid requires more heat to raise its temperature a given number of degrees'than is required at lower tank temperatures, which,

cause tends to introduce into the regulation and recording action an error similar but opposite to the thermometer error. Also the heating value of a given volume of the test gas decreases upon increase in the. degree of dilution thereof with vapor of the sealing liquid, that is to say, upon increase in tank temperature, the resultant error being cumulative withthat due to the aforementioned variation inspecific heat of 'the cooling fluid.

Thus in the present instance, the tendencies to error due to varlation 1n vapor content of the gas and the cooling fluid tend to offset that due to variation in temperatureresistance co-efiicient of the resistance thermometers, .but obviously, in the absence of special provisions, strictly accurateresults will be obtained only if the opposing tendencies to error are of equal value, which condition will seldom arise in practice.

It has however, been demonstratedthat by special construction and calibration of said ,resistance thermometers the tempera-. tine-resistance curve'characterlstlc thereofmay be so varied that the same are adapted to make automatic compensation for all of the three aforementioned tendencies to error, or more accurately the differential of such opposing tendencies, While maintaining the by Letters Patents is:

1. The method of carrying on combustion of fluids, which comprises maintaining a supply of definitely proportioned quantities of such fluids under like conditions of temperature, pressure and saturation, mixing certain of said fluids prior to combustion with less than the total quantity of other of said fluids, and utilizing the remainder of such otther of said fluids to support and assist in the combustion.

2. The method of ascertaining the heating value of a combustible fluid,

portioned quantities of such fluid and other fluid, said fluids being supplied and maintained under like conditions of temperature, pressure and saturation, mixing certain of such fluids, prior to combustion, with less than the total quantity of other of such fluids, and utilizing the remainder of such other of said fluids to support and assist in the combustion. v

3. Apparatus for carryingoncombustion of fluids, comprising'means for maintaining a supply of definitely proportioned quantities of such fluids under like conditions of temperature, pressure and saturation, means for mixing certain of said fluids, prior to combustiomwith less than the total quantity of other of said fluids, and means for utilizing the remainder of such other of said hich COlTl", prises efl'ectmg combustion of definitely profluids to support and assist in the combustion. 1

4. In apparatus for ascertaining the heating value of a combustible fluid, the combination with means for eflectingicombustion of definitely proportioned quantities of such fluid and other fluid supplied and maintained under like conditions of temperature, pressure and saturation, of means for mixing certain of said fluids, prior to combustion, with less than the total quantity of other of said fluids, and means for utilizing the remainder of such other of said fluids to support and assist in the combustion.

5. In apparatus for ascertaining the heating value of a combustible fluid, the combination with a burner, of means to maintain a supply of definitely proportioned quantities of such fluid and other fluid under like conditions of temperature, pressure and saturation, said latter means including means for supplying together to said burner certain of said fluids and a portion less than the total quantity of other of said fluids, means for separately supplying to said burner the remainder of such other of said fluids to support and assist in the combustion, and means for proportioning the sup ply of said other of said fluids between said n two latter mentioned means.

6. A calorimeter, comprising resistance thermometers to be subjected to temperature conditions which differ as a function of the value to be ascertained, means to indicate an efi'ect of such temperature conditions upon said thermometers, the temperatureresistance characteristic of certain of said resistance thermometers being adaptedto vary in accordance with and to compensate for additional temperature variations which would tend to impair the accuracy of the indicationsl Y a 7. A calorimeter, comprising resistance thermometers to be subjected to temperature conditions which differ as,a function of the tained, certain of said elements having.

electro-thermal characteristics such as to compensate for additional variations in temperature thereof incident to changes in the basic temperature of the fluid, and means value to be ascertained, means to indicate an to indicate an effect of such temperature conditions upon said elements.

9. Apparatus for ascertaining the heating value of a flowing combustible fluid, comprising resistance thermometers located at spaced points in the path of said fluid and adapted to be simultaneously subjected to different temperature conditions which vary directly in accordance with a value to be ascertained, said thermometers being also subjected to other like conditions which have a different efiect upon the respective resistance characteristics thereof due to said different temperature conditions, the temperature-resistance characteristics of certain of said thermometers being such as to compensate for, said difference in effect upon said resistance characteristics, and means to indicate an effect of such temperature conditions upon said thermometers.

10. The method of ascertaining the heating value of a flow of combustible gas through combustion of definitely propor-' tioned quantities of said gas and air which comprises maintaining said gas and air at like conditions of temperature, pressure and saturation, mixing said gas, prior to combustion, with a portion of said air insuflicient to support combustion and then directing said mixture and the remainder of said air to the desired point of combustion.

11. In a calorimeter, the combination with wet displacement pumps having a common liquid seal and adapted to supply respectively test gas, combustion air and cooling air, for combustion of the gas and combustion air and absorption, by the cooling air, of the heat so liberated, resistance thermometers to be subjected respectively to the temperature of the cooling fluid before and after the heat exchange, and means to indicate an effect of such temperatures upon said resistance thermometers, said resistance thermometers having means to compensate for variable factors tending to impair the accuracy of the indications, including variations in specific heat of the cooling fluid and in the state of dilution of the gas with vapor of the seal.

12.. In a calorimeter, the combination with wet displacement pumps having a common liquid seal and adapted to supply respectively test gas, combustion air and cooling air, for combustion of the gas and combus tion air and absorption, by the cooling air, of the heat so liberated, resistance thermometers to be subjected respectively to the temperature of the cooling fluid before and after the heat exchange, and means to indicate an effect of such temperatures upon said resistance thermometers, said resistance thermometers having means to compensate for variable factors tending to impair the accuracy of the indications, including variations in temperature of the seal.

' 13. In apparatus for ascertaining the heating value of a combustible fluid, the combination with means for effecting combustion of-a regulable quantity of such fluid, of a Wheatstone bridge having certain of its elements adapted to change their resistance under variable temperature conditions and subjected to temperatures whose difference is a function of a calorific effect of such combustion, said elements being constructed and arranged to maintain substantially a given relation of their respective tempera ture-resistance characteristics throughout the working range, and means controllable by said Wheatstone bridge for indicating the heating value of the fluid.

In witness whereof, I have hereunto subscribed my name.

HORACE N. PACKARD; 

